Soft plastic articles, such as fishing lures, are well known and injection molding of such lures is widely practiced.
Typically, injection molding is accomplished using a mold which has a stationary half and a movable half, each of which carry plurality of matched cavity blocks. Each cavity block has defined therein a chamber which can be filled with plastic and when mated with the matching chamber of the matching cavity block casts a complete article. The plastic is injected into the chambers through a central conduit or gate which feeds several cavity blocks mounted on the mold.
Techniques and uses of such molds in the fishing lure industry allow a wide variety of lures to be cast currently, including artificial worms, lizards, minnows and other insects. Typically, the molds are created by first creating a model of the lure to be cast, such as a wooden model which has been hand carved and using this model to form the cavity in the mold by casting the cavity blocks about the model or a duplicate thereof. The model is retrieved after the mold is cast and hardened. It will be appreciated that the model surfaces must thus be formed such that the model can be removed from the casting intact for use in subsequent castings; accordingly, the model must be oriented in the mold such that no portion of the model is obscured from the parting line of the cavity blocks. Thus, articles which have a downturned tail or other terminal portion which might extend obliquely of the parting line are cast in profile such that the sides of the lure are defined in the cavity block. In this manner, the two sides of a creature may be brought together in the matching cavity blocks and the creature, e. g., a minnow, is made from plastic with its vertical or dorsal plane in alignment with the parting line of the cavity blocks. On a lure with a symmetrical body, this does not present a problem; however, on a lure which is only bilaterally symmetrical, problems can occur when it is desired to form the lure from two plastics having different coloration, wherein the lure is desired with a top color and a bottom color, such as a minnow with a green back and a yellow stomach. If the minnow shape requires profile manufacture of the mold cavity as noted herein above then the manufacturer cannot inject the two colors of plastic to achieve the desired lamination. Consequently, lure manufactures have had to paint or otherwise color the lures after molding to achieve the desired laminated appearance in such lures.